Concurrent request limit for A-Frame <a-assets> element

Goal: Determine the maximum number of simultaneous network requests that the browser will allow when A-Frame’s element preloads several large textures, given that A-Frame relies on the browser’s native loading mechanism and does not expose a configurable concurrency cap.

Constraints: Browser‑imposed limits differ by vendor and protocol (e.g., HTTP/1.x vs HTTP/2), are not documented by A‑Frame, and may shift with changes to the bundled Three.js version across releases. Because A‑Frame does not provide introspection or throttling hooks for asset loads, the exact threshold remains uncertain.

Specific questions: What is the typical concurrent request ceiling for assets loaded via in current browsers? Does A‑Frame offer any way to observe or influence this limit? How does the limit behave across different A‑Frame releases and associated Three.js versions?